In recent years, cameras have been proposed that can reconstruct an image at any focal position designated by users from an imaged data obtained so as to include directional traveling information of light in addition to a light intensity distribution. For instance, NPL 1 proposes a light field camera realizing the above-described function using a method called “light field photography”. NPL 1 adopts an optical system having a configuration where a microlens array is arranged between a photographing lens and an image pickup element to allow light having passed through different pupil areas of the photographing lens to be converged on respective microlenses. A pixel block including a plurality of pixels is assigned to one microlens. Light converged by the microlens is photoelectrically converted by different pixels included in a corresponding block depending on an incoming direction. An image signal corresponding to a ray of light focused on a synthetic image plane (a refocus plane) and arriving at each microlens is extracted from a thus obtained image signal, thereby allowing an image at any focal position to be reconstructed.
In solid-state image pickup elements, such as a CCD image sensor and CMOS image sensor, a defect pixel may be caused by a crystal defect locally existing in the semiconductor substrate. No correct photoelectric conversion output can be obtained from such a defect pixel. Accordingly, the image pickup signal from the defect pixel is required to be corrected.
Conventional methods for correcting an image pickup signal from a defect pixel are, for example, a method of replacing the pixel value of the defect pixel with the pixel value of a pixel adjacent to the defect pixel, and a method of replacing the pixel value of the detect pixel with the average value of pixels adjacent to the defect pixel.